Flow control and pressure regulating device



1951 D. B. GARDINER FLOW CONTROL AND PRESSURE REGULATING DEVICE Filed Aug. 27, 1947 R M mm N. NR c m M a 1/? N f I B. j qmu p y N A o- @Q o mm. 9 c N N! m: .VQM W on D g l a o I 3, o2 mm OP wm mm 8 mm A74 1 I. m? Am i 3 3 No a ATTORN EY Patented Oct. 30, 1951 FLOW CONTROL AND PRESSURE REGULATING DEVICE Duncan B. Gardiner, Detroit, Mich., assignor to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application August 27, 1947, Serial No. 770,883

This invention relates to power transmissions, particularly to those of the type comprising two or more fluid pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

Th invention is generally concerned with a power transmission system for driving a plurality of fluid motors having different fluid volume and pressure requirements. In particular, the invention is concerned with a transmission of the abov character wherein it is necessary to drive at least one of the motors at a regulated rate of speed and, in addition, at a reduced pressure.

It is an object of this invention to provide a device for a transmission as above described which may be connected to a high pressure fluid source and which will deliver fluid at a regulated volume and at a reduced pressure.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form of the present invention is clearly shown.

In the drawing:

The single figure is a diagrammatic view of a hydraulic power transmission system embodying a cross-sectional view of a preferred form of the present invention.

Referring now to the drawing, there is shown a variable delivery pump I0 which may be driven by an electric motor (not shown). The pump I0 is connected to a tank I2 by a suction conduit I4 and is also provided with a delivery conduit I6 which is connected to a pressure port I8 of a closed center type four-way directional valve 20 and also to an inlet port 22 of a flow control and pressure regulating device 24.

A branch conduit 26 of the pump delivery conduit I6 is connected to an actuating piston 28 which is mechanically linked to the pump III for varying the volume thereof in the conventional manner.

The control valve 20 is also provided with tank ports 30 and SI which are connected to the tank I2 by conduits 32 and 33 and is also provided with motor ports 34 and 35. The motor ports 34 and 36 are connected to the head and piston rod ends of a, piston cylinder motor 38, respectively, by means of conduits 40 and 42.

The device 24 is provided with an outlet port 44 which is connected to a pressure port 46 of a closed center type four-way directional valve 48 by a conduit 50. The directional valve 48 is provided with tank ports 52 and 53 which are connected to the tank I2 by conduits 54 and 55. The

Claims. (Cl. 60-97) valve 48 also has motor ports '56 and 58 which are connected to the rod and head ends of a piston cylinder motor 80, respectively, by conduit-s 62 and 64. A suitable relief valve 66 is incorporated in the conduit 50 and will exhaust excessive pressure fluid caused by temperature expansion to the tank I2 by means of an exhaust conduit 10 connected to the conduit 54. y

The device 24 is provided with an inlet passage I2 which connects the inlet port 22 to an inlet chamber I4 and also an outlet passage I6 which connects an outlet chamber I8 with the outlet port 44. Incorporated in the outlet passage T5 is a suitable adjustable throttle 80.

For the purpose of maintaining a regulated flow rate through the throttle 80, there is provided a pressure compensating valve 82 which comprises a piston '84 connected to which is a stem 86 having lands 88 and 90. The land 90 is adapted to control the flow of fluid from the inlet chamber 14 to the outlet chamber I8 by controlling the opening of a seat 92. The outlet chamber I8 ahead of the throttle is connected to a chamber 94 on the under side oi. the piston 84 by a passage 96. The outlet passage 16 beyond the throttle 80 is connected to a chamber 98 located above the piston 84 by a passage I00. A spring I02, mounted in the chamber 98, biases the piston 84 so that the inlet valve opens the seat 92.

The compensating valve 82 is adapted to be responsive to the pressure ahead of and beyond the throttle 8II so as to maintain a constant pressure drop across the latter. The pressure drop is determined by the setting of the spring I02.

For the purpose of preventing the pressure beyond the throttle 80 from increasing beyond a predetermined maximum, provision is made for closing the compensating valv by means of a floating pin I04. The pin I04, which is shiftable within a bore I06 of a member I08, rests on a piston IIO which is shiftable on a guide member II2. Guide member H2 is provided with a pressure fluid passage I I4 leading directly to the under side of the piston H0. The passage H4 is opened and closed to communication with the passage 16 beyond th throttle 80 by means of a pressure responsive control valve indicated by the numeral I I6.

The valve H6 is shiftable within a sleeve II8 provided with ports I20 and I22, the former of which is connected to the piston passage H4 and the latter of which acts as a drain port I22. The valve H6 is also provided with a land I 24 at its right end having a recess I28 which breaks over the port I20 when the valve H6 is shifted leftwardly. For the purpose of shifting the spool leftwardly, there is provided a pressure chamber I28 at the right end of valve II8 which is connected to the outlet passage I6 beyond the throttle 80 by means of a passage I30 and a passage I82 in alignment with the latter. Thus, the right end of valve H8 is in continuous communication with the outlet passage 18 beyond the throttle 80. However, a pressure at the outlet 44 of the device 24 equivalent to the resistance of a spring I34 which biases valve II6 to the closed position must occur before the control valve II8 will shift leftwardly to admit pressure to the piston passage II4.

The valve H8 is also provided with a longitudinal passage I38 in alignment with a passage I38 in a spring retainer I40. Fluid displacement caused by the shifting of the valve H6 is free to flow through the passages I38 and I38 to the sleeve port I22 by means of a transverse passage I. The port I20 is connected in the position of the valve shown to sleeve port I22 by a groove I42 in the valve H8. The port I22 is connected by a passage I44 to a chamber I48 within the member I08 and which surrounds the piston H0. The chamber I48 is connected to the tank I2 by means of a passage I48 connected to a drain port I50 and a conduit I52 connected to the port I50 and the tank I2.v

I The motor 60, as shown, has a smaller fluid displacement than that of motor 38 although this relation is not necessary. In addition, it should be assumed that it is desirable to operate the load device (notshown) driven by the motor 60 at a regulated rateof speed and that the pressure required is less than that created in the other part of the system ahead of the flow control and pressure regulating device 24.

With the pump I running and the control valves 20 and 48 shifted so as to direct pressure fluid to the head end of both motors, the operation of the transmission is as follows:

, Pressure fluid will be delivered by the pump I0 by means of the delivery conduit I8 to the pressure port I8 of the control valve 20. Pressure fluid is directed by the control valve 20 by means of motor port 34 to the conduit 40 and the head end of motor 38. F'luid discharging from the rod end of motor 38 is free to flow to tank I2 by means of conduit 42, motor port 38 and tank port 30 of control valve 20, and the conduit 32. Simultaneously, pressure fluid is also delivered by the pump I0 to the inlet port 22 of the device 24.

The throttle 80 will have originally been adjusted to a predetermined setting. As pressure fluid flows from the inlet port 22 to the outlet port 44 of the device 24, the compensating valve 82 will maintain a constant pressure drop across the throttle 80 so as to maintain the flow through the throttle 80 constant. Fluid flows through the inlet port 22 to the outlet port 44 by means of inlet passage I2, inlet chamber I4, seat 92, outlet chamber I8, and outlet passage I8 within which is incorporated throttle 80. Any increase or decrease of pressure in the chamber I8 is immediately present in chamber 84 by means of passage 98 connected to the outlet chamber I8. The land 90 controls the opening of the seat 92 and assumes various regulating positions between the fully open and fully closed positions so as to admit more or less fluid to the outlet chamber and maintain the pressure drop across the throttle 80 constant and the flow therethrough regulated. This regulated flow is delivered to the head end of motor 60 by means of conduit 50, ports 46 and 58 of control valve 48, and the conduit 84. Fluid displaced from the rod end of the motor 60 is free to discharge to the tank I2 by means of conduit 62, the ports 58 and 52 of control valve 48, and the conduit 54.

The compensating valve not only cooperates with the throttle 80 to maintain a uniform regulated flow rate reduced in volume with that flowing to the motor 38, but in addition acts as a pressure reducing valve. In operation, the valve .80 restricts the opening of the seat 82 so that the pressure existing ahead of the compensating valve 82 in the rest of the system is reduced when it enters the outlet chamber I8. That is, a pressure drop occurs across the seat opening 82.

There is a further pressure drop across the throttle 80 which is determined by the setting of the spring I02. Consequently, the flow rate to the motor 80 is not only being constantly regulated at a volume less than that flowing to the motor 38, but in addition the pressure is condetermined by the load resistance encountered by motor 80 and may be any value from zero up to a preset maximum. The maximum pressure at the outlet of the device 24 is determined by the resistance of the spring I34 which biases the control valve IIG to the closed position. If,

at any time, the pressure at the outlet of the device 24 reaches this predetermined maximum,

the control valve II6 shifts leftwardly and pressure fluid is admitted by the valve to the piston passage H4. The piston H0 is thereupon shifted upwardl and the floating pin I04 shifts upwardly therewith to shift the compensating valve 82 upwardly, and the valve 90 to the closed position. Valve 90 closes the seat 82 and prevents flow from the inlet chamber I4 to the outlet chamber I8. When the pressure decreases below the setting of the spring I34, the spring shifts the control valve I I6 rightwardly, and the piston I I0 together with the pin I04 shifts downwardly to permit the compensating valve to operate once again in a normal manner.

If the control valves 20 and 48 are shifted to reverse the direction of the motors 38 and 80 the device 24 will operate in the same manner for regulating the volume to the motor 80 at a reduced rate and at a reduced pressure.

If the control valve 48 is shifted to the closed center position, and the control valve 20 is shifted from the closed center position, fluid is delivered from the pump I0 only to the motor 38 and the device 24 does not in any manner interfere with its operation.

If the control valve 28 is shifted to the closed center position and the control valve 48 shifted from the closed center position, fluid from the pump I0 is delivered only to the motor 60 in such volume and at a pressure regulated by the device It should thus be noted that the device 24,

1 when connected to a high pressure fluid source,

will efficiently deliver fluid at a regulated volume and at a regulated reduced pressure.

While the form of embodiment of the inven mechanism comprising in combination a. housing having an inlet adapted to be connected to a high pressure fluid source and an outlet through which fluid is adapted to flow at a substantially uniform volume and at a reduced pressure to be maintained below a predetermined maximum. in series between the inlet and the outlet a throttle and a pressure compensating valve the latter of which is responsive to the pressure drop across the throttle for reducing the pressure from that at the inlet and for maintaining a substantially uniform flow rate through the throttle, and pressure responsive means for closing the compensating valve and blocking flow from the inlet to the outlet upon predetermined increases 7 of pressure beyond the throttle.

2. A flow control and pressure regulating mechanism comprising in combination a housing provided with a flow passage having an inlet adapted to be connected to a high pressure fluid source and an outlet through which fluid is adapted to flow at a substantially uniform volume and reduced pressure to be maintained below a predetermined maximum, in series in the flow passage an adjustable throttle and a pressure compensating valve the latter of which is responsive to the pressure drop across the throttle for reducing the pressure from that at the inlet and for maintaining a substantially uniform flow rate through the throttle, and means responsive to pressure changes in the flow passage beyond the throttle for operating the compensating valve to the closed position to maintain the pressure beyond the throttle below a predetermined maximum.

3. A flow control and pressure regulating mechanism comprising in combination a housing provided with a flow passage having an inlet adapted to be connected to a high pressure fluid source and an outlet through which fluid is adapted to flow at a substantially uniform volume and reduced pressure to be maintained below a predetermined maximum, in series in the flow passage an adjustable throttle and a pressure compensating valve the latter of which is responsive to the pressure drop across the throttle for reducing the pressure from that at the inlet and for maintaining a substantially uniform flow rate through the throttle, and means operatively associated with the compensating valve responsive to predetermined pressure increases beyond the throttle for closing the compensating valve until the pressure beyond the throttle falls below a predetermined maximum.

4. In a hydraulic power transmission having a constant pressure fluid source and a plurality of fluid motors at least one of which has substantially uniform volume displacement and reduced limited pressure requirements the combination therewith of a flow control and pressure regulating device comprising a housing having an inlet connected to the fluid source, an outlet connected to one of the motors, a flow passage connecting the inlet to the outlet, in series in said passage an adjustable throttle and a pressure compensating valve responsive to the pressure drop across the throttle for reducing the pressure at the outlet from that at the inlet and maintaining a uniform flow rate through the throttle, and means operatively associated with the compensating valve responsive to predetermined pressure increases beyond the throttle and closing the compensating valve until the pressure beyond the throttle falls below a predetermined maximum.

5. In a hydraulic power transmission having a constant pressure fluid source and a plurality of fluid motors atleast one of which has substantially uniform volume displacement and reduced limited pressure requirements the combination therewith of a flow control and pressure regulating device comprising a housing having an inlet connected to the fluid source, an outlet connected to one of the motors, a flow passage connecting the inlet to the outlet, in series in said passage an adjustable throttle and a 'pressure compensating valve responsive to the pressure drop across the throttle for reducing the pressure at the outlet from that at the inlet and maintaining a substantially uniform flow rate through the throttle, and pressure responsive means for closing the compensating valve and blocking flow from the source to the outlet when the pressure at the outlet has reached a predetermined maximum.

DUNCAN B. GARDINER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,467,522 Amsler Sept. 11, 1923 1,593,601 Rush July 27, 1926 1,620,881 Fisher Mar. 15, 1927 2,102,865 Vickers Dec. 21, 1937 2,139,050 Vickers Dec. 6, 1938 2,291,731 Lake et al Aug. 4, 1942 2,306,379 Conradson Dec. 29, 1942 2,328,980 Herman et al. Sept. 7, 1943 2,331,026 Harrington Oct. 5, 1943 

